The effect of cardiac glycosides to increase cardiac inotropy by altering Ca(2+) cycling is well known but still poorly understood. The studies described in this report focus on defining the effects of ouabain signaling on sarcoplasmic reticulum Ca(2+)-ATPase function. Rat cardiac myocytes treated with 50 microM ouabain demonstrated substantial increases in systolic and diastolic Ca(2+) concentrations. The recovery time constant for the Ca(2+) transient, tau(Ca(2+)), was significantly prolonged by ouabain. Exposure to 10 microM H(2)O(2), which causes an increase in intracellular reactive oxygen species similar to that of 50 microM ouabain, caused a similar increase in tau(Ca(2+)). Concurrent exposure to 10 mM N-acetylcysteine or an aqueous extract from green tea (50 mg/ml) both prevented the increases in tau(Ca(2+)) as well as the changes in systolic or diastolic Ca(2+) concentrations. We also observed that 50 microM ouabain induced increases in developed pressure in addition to diastolic dysfunction in the isolated perfused rat heart. Coadministration of ouabain with N-acetylcysteine prevented these increases. Analysis of sarcoplasmic reticulum Ca(2+)-ATPase protein revealed increases in both the oxidation and nitrotyrosine content in the ouabain-treated hearts. Liquid chromatography-mass spectrometric analysis confirmed that the sarcoplasmic reticulum Ca(2+)-ATPase protein from ouabain-treated hearts had modifications consistent with oxidative and nitrosative stress. These data suggest that ouabain induces oxidative changes of the sarcoplasmic reticulum Ca(2+)-ATPase structure and function that may, in turn, produce some of the associated changes in Ca(2+) cycling and physiological function.

Acute pulmonary embolism (APE) is frequently reported in patients with cardiac arrest (CA) in emergency care. Pneumocyte apoptosis is commonly observed in the lungs following an APE. An important pathological mechanism evoking apoptosis during a lipopolysaccharide-induced acute lung injury is the angiotensin-converting enzyme 2 (ACE2)/ACE imbalance. The present study uses a porcine model to examine the anti-apoptotic effects of captopril on APE-CA and the return of spontaneous circulation (ROSC). Pigs were randomly assigned into four groups: Control, APE-CA, ROSC-saline, and ROSC-captopril. Surviving pigs were euthanized at 6 h and lungs were isolated for analysis using several biochemical assays. Compared with the control group, the ACE2/ACE ratio was lower in the APE-CA and ROSC pigs. In addition, APE-CA pigs had higher Bcl-2-associated X protein (Bax) and cleaved caspase-3 levels, and lower B-cell lymphoma-2 (Bcl-2) level compared to control pigs. Captopril treatment reduced lung apoptosis, as demonstrated by lower TUNEL-positive cells, higher Bcl-2, and lower cleaved caspase-3 protein levels in the lung. Notably, the ACE2/ACE ratio was positively correlated with Bcl-2 protein levels and Bcl-2/Bax ratio. In conclusion, captopril has a protective effect against lung apoptosis following ROSC and that maintaining the balance of the ACE2/ACE axis is important for inhibiting pulmonary apoptosis during APE.

Long-term use of antibiotics for septic patients leads to bacterial resistance, increased mortality, and hospital stay. In this study, we investigated an emerging biomarker presepsin-guided strategy, which can be used to evaluate the shortening of antibiotic treatment in patients with sepsis without risking a worse outcome. Methods: In this multicenter prospective cohort trial, patients were assigned to the presepsin or control groups. In the presepsin group, antibiotics were ceased based on predefined cut-off ranges of presepsin concentrations. The control group stopped antibiotics according to international guidelines. The primary endpoints were the number of days without antibiotics within 28 days and mortality at 28 and 90 days. Secondary endpoints were the percentage of patients with a recurrent infection, length of stay in ICU and hospital, hospitalization costs, days of first episode of antibiotic treatment, percentage of antibiotic administration and multidrug-resistant bacteria, and SOFA score. Results: Overall, 656 out of an initial 708 patients were eligible and assigned to the presepsin group (n ¼ 327) or the control group (n ¼ 329). Patients in the presepsin group had significantly more days without antibiotics than those in the control group (14.54 days [SD 9.01] vs. 11.01 days [SD 7.73]; P < 0.001). Mortality in the presepsin group showed no difference to that in the control group at days 28 (17.7% vs. 18.2%; P ¼ 0.868) and 90 (19.9% vs. 19.5%; P ¼ 0.891). Patients in the presepsin group had a significantly shorter mean length of stay in the hospital and lower hospitalization costs than control subjects. There were no differences in the rate of recurrent infection and multidrug-resistant bacteria and the SOFA score tendency between the two groups. Conclusions: Presepsin guidance has potential to shorten the duration of antibiotic treatment in patients with sepsis without risking worse outcomes of death, recurrent infection, and aggravation of organ failure. Trial registration: ChiCTR, ChiCTR1900024391. Registered 9 July 2019-Retrospectively registered, http://www.chictr.org.cn